MEGA UPDATE OF THE DEATH !!!!    

I splited the librairy in two part, mostly to decrease the total program weight
GCORE : the main lib, contains most of basic 3d function
GPOLY : the polygons handling lib

I simply rewamped all the librairy. Polygons gestion is now a LOT better, as well as 3d processing.

A lot of things is planed :
A GOBJCT lib, to have an object gestion
GPORTAL lib : portal rendering !
some new function in the GPOLY lib...

I you have any problem, just ask me.

In the zip, you can find:
prgmGCORE and prgmGPOLY, the lib
prgmGEXAMPLE : GPOLY lib example
prgmGCUBE : GCORE lib example

compile with  axe 1.2.1a !

Last thing to say : I have not fully tested all the commands, so there can still bugs.
MAKE SURE TO BACKUP ALL YOUR DATA BEFORE USING GLIB !

Can you draw stretched sprites in 3d space that always face the player and optimize those routines so they aren't just transformed walls with textures on them? Might make the overall experience smoother.

Hopefully Keoni's suggestion could help. That's how sprites are in DOOM (and even some Nintendo 64 games, such as trees in Super Mario 64) and it doesn't remove much from the game experience, especially at lower resolutions where it isn't as noticeable.

Indeed. You save 3 vertices per sprite if you do it this way instead of using textures on a wall that's facing the player. It also saves you some calculations regarding the translation of the wall in order to appear orthogonal to the player's view direction.

Do you mean stuff like dynamic lightning depending of your viewing angle or walls being darker when opposed to the sun??

I dynamic light depending of the view point, and I reuse part of backface culling

It's not an axiom, it's an Axe library.

Apart from that, OMGWTFLOLBBQ

Seeing the speed, I think this is 15 MHz ... Because a single textured face was around 6 FPS at 6 MHz.

Either way, I have to create a new word to describe the level of awesomeness of this.